The overall objectives of this project are to define more precisely the different types of immunologic reactions that may take place in the cornea and the manner in which these may cause damage to corneal tissue; to clarify further the mechanisms involved in the immunologic destruction of corneal grafts; and to relate these immunopathologic processes to problems of clinical importance. The goals for the current year were to extend our earlier observations on the mechanism of endothelial cell destruction by sensitized lymphoid cells, such as plays so important a role in the rejection of corneal allografts, employing both in vivo and in vitro model systems. Our research goals for the coming year include an extension of the studies on the graft-versus-host model of corneal endothelial destruction. We would like to confirm, if possible, a suggestion in an earlier report that foreign lymphocytes may actually enter into an endothelial cell, and effects its destruction from within, as well as from interaction on its surface membrane. In addition, we are attempting to establish a model system to assess whether immunologic reaction between a sensitized lymphocyyte and its specific antigen in proxmity to "innocent bystander" endothelial cells may result in damage to those cells, since in any immunopathologic process it is always difficult to determine to what extent the local tissue damage is specific and to what extent it is merely a spillover of some unrelated process occurring close by. BIBLIOGRAPHIC REFERENCES: Induction of corneal graft rejection by passive cell transfer. A.A. Khodadoust and A.M. Silverstein, Invest. Opthalmol. 15:89, 1976.